Drivers "No Audio Device" issue

I recently got a new computer. It's running XP service pack 3. The sound doesn't work, and when I go to Control Panel>Sounds and Audio Devices, it says there is no audio device. The sound was working fine before I plugged in the graphics card I had in my previous computer. The graphics card is a Radeon 4550 (something like that, I bought it quite a while ago and I don't have the box). No idea what to do here, I hope someone knows how to fix it :'(

Just ask if you need more info about the computer.

I should also mention that when I try to install SoundMax drivers it gives me an error saying the audio driver files don't support my hardware.